In the study of prostaglandins (abbreviated as PG hereafter), many important discoveries have been made continuously in recent years. And so it was found a large change in the direction of the research and development of PG. In the compounds which have been newly found or newly confirmed their structure in PG family, it can be said that PG endoperoxides, (i.e. PGG.sub.2 and PGH.sub.2), thromboxane A.sub.2 (abbreviated as TXA.sub.2 hereafter), prostacyclin (i.e. PGI.sub.2) and leukotriene C.sub.4, D.sub.4 and E.sub.4 (abbreviated as LTC.sub.4, LTD.sub.4 and LTE.sub.4, respectively, hereafter) etc. have especially strong and unique biological activities.
All the compounds of PG family containing various PG previously known well in addition to the above compounds, are biosynthesized from the same mother compound, i.e. arachidonic acid in a living body and, therefore, the metabolic routes starting from arachidonic acid is called "Arachidonate cascade" as a whole. The detailed explanation of each route and the pharmacological character of each metabolite are described in Igaku No Ayumi, 114, 378 (1980), ibid, 114, 462 (1980), ibid, 114, 866 (1980), ibid, 114, 929 (1980), Gendai Iryo, 12, 909 (1980), ibid, 12, 1029 (1980), ibid, 12, 1065 (1980) and ibid, 12, 1105 (1980) etc.
The arachidonate cascade can be largely divided into two routes; one is the route that cyclooxygenase acts on arachidonic acid to convert, into various PGs, e.g. prostaglandin F.sub.2 (abbreviated PGF.sub.2 hereafter), prostaglandin E.sub.2 (abbreviated PGE.sub.2 hereafter), PGI.sub.2, TXA.sub.2, via PGG.sub.2 and further PGH.sub.2 and the other is the route that lipoxygenase acts on arachidonic acid to convert, in hydroxyeicosatetraenoic acid (abbreviated as HETE hereafter) or leukotrienes, via hydroperoxyeicosatetraenoic acid (abbreviated HPETE hereafter).
As the former route is well known, it is not described in the present specification in detail. See Prostaglandin (1978), edited by Makoto Katori et al., published by Kohdan-sha.
Concerning the latter route, it has been known that various compounds are produced according to the following scheme I. ##STR4##
Besides being metabolized through a well known route, i.e. the route via PG endoperoxides, arachidonic acid is also metabolized through another route by the action of lipoxygenase. That is to say, arachidonic acid is metabolized by the action of lipoxygenase, e.g. 5-lipoxygenase, 12-lipoxygenase and 15-lipoxygenase, to 5-HPETE, 12-HPETE and 15-HPETE, respectively.
These HPETE are converted into 5-HETE, 12-HETE and 15-HETE, respectively, by the action of peroxidase converting a hydroperoxy group into a hydroxy group. Furthermore, LTA.sub.4 is also produced from 5-HPETE by dehydration. LTA.sub.4 is converted into leukotriene B.sub.4 (abbreviated as LTB.sub.4 hereafter) or LTC.sub.4 enzymatically. Further, LTC.sub.4 is converted into LTD.sub.4 by the action of .gamma.-glutamyl transpeptidase.
Moreover, it was recently defined that LTD.sub.4 is metabolized to LTE.sub.4 (see Biochem. Biophys. Res. Commun., 91, 1266 (1979) and Prostaglandins, 19(5), 645 (1980)).
Besides, SRS is an abbreviation of Slow Reacting Substance and it was named by Feldberg et al. for the substance released when perfusing cobra venom through isolated lung or incubating cobra venom with vitellus. And it was reported that the substance constricted ilem isolated from guinea pig slowly and continually (see J. Physiol., 94,187 (1938)).
Moreover, Kellaway et al. showed the relation between SRS-A and allergic reaction from the fact that SRS-A is released when an antigen is sensitized to perfusing lung isolated from guinea pig (see Quant. J. Exp. Physiol., 30, 121 (1940)).
Brocklehurst reported that when the antigen is sensitized to a lung fragment isolated from a bronchial asthmatics whose specific antigen is defined, by an operation, histamine and SRS-A are released and strongly constrict bronchial muscle. Since such constriction can not be prevented by an antihistaminic agent, he suggested that SRS-A is an important bronchoconstrictor in an asthmatic paroxysm (see Progr. Allergy, 6, 539 (1962)).
Since then, many reports were published, for instance, SRS-A prepared from human lung slice constrict a tracheal spiral of normal human (see Int. Arch. Allergy Appl. Immunol., 38, 217 (1970)); when SRS-A prepared from rats is injected intravenously to guinea pig, significant increase of pulmonary resistance is observed (see J. Clin. Invest., 53, 1679 (1974)); in addition, a subcutaneous injection of SRS-A to guinea pig, rat and monkey enhances vascular permeability (see Advances in Immunology, 10, 105 (1969), J. Allergy Clin. Immunol., 621,371 (1978), Prostaglandins, 19(5), 779 (1980) etc. ) .
Generally, the substance released by immunological reaction is called SRS-A. On the other hand, the substance released by non-immunological reaction such as calcium ionophore is called SRS. However, the above two substances have many similarities to each other and, therefore, it is considered they would probably be the same substance.
Further, it was confirmed that SRS or SRS-A is a mixture of LTC.sub.4 and LTD.sub.4. So it can be understood that the pharmacological characters of these leukotrienes are the same as those of SRS or SRS-A (see Proc. Natl. Acad. Sci. USA, 76, 4275 (1979), Biochem. Biophys. Res. Commun., 91, 1266 (1979), Proc. Natl. Acad. Sci. USA, 77, 2014 (1980) and Nature, 285, 104 (1980)).
Based on results of these studies, various leukotrienes (the structures of LTC.sub.4, LTD.sub.4 and LTE.sub.4, and further other leukotrienes which may be confirmed in the future) biosynthesized from arachidonic acid via LTA.sub.4, are considered to be important factors relating to the appearance of allergic tracheal and bronchial diseases, allergic lung diseases, allergic shock and various allergic inflammations.
To suppress leukotrienes is useful for the prevention and/or treatment of tracheal bronchial or lung diseases such as asthma, allergic lung diseases, allergic shock or various allergic diseases.
On the other hand, arachidonic acid is released from phospholipids by the action of phospholipase, and two routes were generally accepted that (1) one is the route that phospholipase A.sub.2 is reacted on phosphatidyl choline, and (2) the other is the route that phospholipase C was reacted on phosphatidyl inositol to produce 1,2-diglyceride, and diglyceridelipase followed by monoglyceridelipase were reacted on it to release arachidonic acid (see Kagaku to Seibutsu (Chemistry and Biology), 21, 154 (1983)).
And it was known that arachidonic acid released is metabolized through two different routes i.e. (1) metabolizing route to bioactive substances e.g. prostaglandins (PGs), thromboxane A.sub.2 (TXA.sub.2) by cyclooxygenase, and (2) metabolizing route to bioactive substances e.g. SRS-A (Slow Reacting Substances of Anaphylaxis), hydroxyeicosatetraenoic acid (HETE) and leukotriene B.sub.4 (LTB.sub.4) by lipoxygenase (see Kagaku to Seibutsu (Chemistry and Biology), 21, 154 (1983)).
These metabolites are known as chemical mediators; for example, TXA.sub.2 is a compound which have a potent activity of platelet aggregation and aotra contraction, SRS-A is a chemical mediator on asthma, LTB.sub.4 is a chemical mediator on various inflammations (e.g. gout), and PGs are also chemical mediators on various inflammations which enhance a vascular permeability and a pain, and have a vasodilative action, pyrogenetic action and chemotactic action (see Prostaglandin (1978), edited by Makoto Katori et al, published by Kohdan-sha).
Arachidonic acid is converted and metabolized to various chemical mediators which act important physiological part in living body. And it was known that ill-balances of those chemical mediators induce various disorders.
And as antagonist of SRS, the groups of the compounds of general formula: ##STR5## (wherein from R.sup.1 to R.sup.5 and R.sup.7 each represent a hydrogen atom, a hydroxy group, an alkyl group of from 1 to 6 carbon atom(s), an alkoxy group of from 1 to 6 carbon atom(s), an amino group, an acyl group, an acylamino group of from 2 to 6 carbon atoms, an alkenyl group of from 2 to 6 carbon atoms, a halogen atom or a phenylalkoxy group in which alkoxy have from 1 to 6 carbon atom(s); X represents a hydrocarbyl group of from 1 to 10 carbon atom(s) being optionally substituted by hydroxy group(s); A represents an oxygen atom or is absent; Q represents an alkylene, alkenylene or alkynylene group of from 2 to 6 carbon atoms which may be branched; D represents a carboxy group, a 5-tetrazolyl group or carbamido-5-tetrazolyl group.) were described in patent publications by Fisons Co., Ltd. Japanese patent Application No. 55-1273841, European Patent Publication No. 17332 or U.S. Pat. No. 4,281,008).
And, the following compounds were described in the patent application by Kissei Pharmaceutical Co., Ltd, as anti-allergic agent, of the general formula: ##STR6## (wherein R.sup.1 and R.sup.2 each represent a hydrogen atom or an alkyl group with 1-4 carbon atoms; R.sup.3 and R.sup.4 each represent a hydrogen atom or may be combined together to form an additional chemical bond; X represents a hydroxyl group, a halogen atom, a straight or branched chain saturated or unsaturated alkyl group with 1-4 carbon atoms, a straight or branched chain saturated or unsaturated alkoxy group with 1-4 carbon atoms, an acyloxy group with 1-4 carbon atoms, or a cycloalkyl group with up to 6 carbon atoms; n is zero or an integer of 1-3 with the proviso that when n is 2 or 3; X's may be the same or different and that when two X's are commonly the alkyl or alkoxy group, both X's may be combined together to form a ring; and Y represents a straight or branched chain alkylene group or a straight or branched chain oxyalkylene group connected to the benzene nucleus through an oxygen atom.) as well as physiologically acceptable salts thereof. (see U.S. Pat. No. 4,026,896.)
And benzamides, i.e. compounds represented by the general formula (I) depicted hereafter, were described wherein the symbol B is opened and R.sup.4 is a group of the formula: --OCH.sub.2 COOR, in prior patent applications by the present inventors (see Japanese Patent Application (Kokai) Patent Application Nos. 60-97946, 60-116657, 60-142941 and 60-146855.